Core box vent



P 1949- P. B. COPELAND ET AL 2,482,321

CORE BOX VENT Filed April 8, 1947 H. L. MORRIS P. B. COPELAND INVEN 0R3 AT TORNEY.

Patented Sept. 20, 1949 CORE BOX VENT Paul Bernard Copeland and Harry L. Morris, Detroit, Mich., assignors to Ford Motor Company, Dearbom, Mich., a corporation of Delaware Application April 8, 1947, Serial No. 740,186

4 Claims.

This invention is concerned with the foundry art and more particularly with a core box vent designed to be installed in a core box. The purpose of core box vents is to permit the escape of the air employed in blowing the sand into the core box. This air must be vented, of course, without permitting the escape of sand.

In the mass production of foundry cores, it has become established practice to fabricate such cores by blowing a mixture of the core material which is basically moist sand and a binding agent into a core box the interior of which is shaped so as to impart the desired contour to the core molded therein. In order to fill the core box rapidly and to secure a satisfactorily compacted core it has been found to be necessary to use air under considerable pressure to transport the sand into the core box. Since the core box is, of course, initially filled with air, an escape must be provided for this air, as well as for the air used in transporting the sand. The amount of sand carried out of the core box with the escaping air must be held to a minimum. The core box vent should not appreciably mar the smooth surface of the core box. This subject has received considerable attention in the past as various forms of vents have been devised, the commonest being a simple bronze screen secured in the side of the core box. United States Letters Patents 2,060,350, 2,126,097, 2,176,328 and 2,238,506 may be cited as typical of the efforts to provide a satisfactory core vent, These core vents are exposed constantly to highly abrasive conditions and ordinarily must be frequently replaced. This abrasive action of course results from the fact that some sand is unavoidably driven through the core vent each time the core box is filled. Since these core vents must be frequently replaced and since many are required for each core box, it is apparent that the cost of each individual core box vent must be kept to a minimum.

Accordingly it is an object of this invention to provide a core box vent which will be economical to produce, durable and highly eilicient in use and quickly and easily applied to the core box.

A further object of this invention is the provision of a core box vent which will permit the escape of a maximum volume of air with a minimum of back pressure and which will effectively retain the sand.

It is a. further object of this invention to provide a core box vent which will mar the smooth surface of the cores to the least possible extent.

It is a further object of this invention to provide a resilient core box vent which will i r te 2 more or less constantly while venting air and so will possess self-cleaning characteristics.

With these and other objects in view, the invention comprises the arrangement, construction and combination of the various elements of the structure described in the specification, claimed in the claims and illustrated in the accompanying drawings, in which:

. Figure 1 is a plan view of applicants spiral spring vent element.

Figure 2 is a sectional view of applicants spiral spring element taken parallel to the axis.

Figure 3 is a plan view of the spring receptacle,

Figure 4 is a sectional view of applicants core vent shell.

Figure 5 is a cross section of a completed core ven Figure 6 is a sectional view of applicants core box vent assembled in a core box and as seen at the conclusion of the sand filling operation,

Figure 7 is a sectional view of an optional form of spiral spring member.

In Figure 1 is shown the spiral spring'which is the distinguishing feature of applicants invention. In the drawings this element has been shown on an enlarged scale, the diameter preferred being about five-eighths of an inch. As is more clearly shown in Figure 2 this spring is of flat contour and of vaulted construction. This spring is heat-treated to a hardness which should be equal to at least 50 Rockwell C. These springs are vaulted so that the innermost convolution-is ofi'set axially from the outermost convolution a substantial amount. It is preferred that this offset be about one-quarter of an inch.

Similarly, the vent body I I is shown in plan in Figure 3 and in section in Figure 4. This vent body II is provided with a spring receptacle I2 and a pin socket I3. Figure 5 ShOWs the spiral spring I0 assembled into vent body I I and resting in spring receptacle I2. Pin It has been inserted and peened into place. The purpose of this pin is to support the inner convolutions of spiral spring I0 while in use.

Figure 6 shows applicants core box vent assembled and in place in core box wall I5. This drawing shows the structure at the conclusion of the core box blowing step. It will be noted that the pressure of the sand and air has flattened the vaulted structure of the spiral spring so that the inner convolutions approximate pin I4. In this position there is a minimum of departure of the surface of the core from its normal contour at the spot the vent is inserted.

F 5 7 is a cross section of an optional form producible by ties on the surface of the core due to distortion v under pressure.

Applicants vaulted spiral spring structure is particularly successful in screening out sand and permitting a free flow of air. It is thought that this highly effective screening action is due to the fact the spring member is free to vibrate both axially and radially under the influence of the stream oi! escaping air. However, the use of unvaulted springs is also contemplated by applicants invention.

Applicants core box vent body has been designed for ready manufacture from prefabricated tubing or bar stock on automatic machinery. All of the surfaces are surfaces oi! revolution and are simple turning operations. The spiral spring element is added to the core box vent body by simplyv slightly compressing the spring and inserting it until it rests upon the shoulder at the base of the spring receptacle. The spring tension is suflicient to prevent accidental detachment of the spiral spring from the core box vent body. However, in event of wear or breakage, the spiral spring element is quickly and easily replaced with only the most elementary tools.

This core box vent is easily applied to a core box since the core box vent body is machined to give a good press fit in suitable openings in the core box. To enhance the wear resistance, either the entire core box vent, or the spiral spring may be given a coating of elastomer. Such may be conveniently applied as a rubber cement.

We claim as our invention:

'1. A core box vent comprising a hollow cylindrical shell one end of which has been provided with an internal shoulder, and aspiral resilient filtering member resting upon said shoulder and being held in place only by its spring tension.

2. A core box vent comprising a hollow cylindrical shell one end of which is provided. with an internal shoulder, and a spiral resilient filtering member resting upon said shoulder and being held in place only by its spring tension, said spiral resilient filtering member being vaulted with the apex of the vault so disposed that pressure tending to flatten the resilient member will press said member against said shoulder.

3. A core box vent comprising 'a hollow cylindrical shell one end of which is internally provided with protruding means, and a spiral resilient filtering member resting upon said protruding means and being held in place only by its spring tension, said spiral resilient filtering member being vaulted with the apex of the vault so disposed that pressure tending to flatten the resilient member will press said member against said protruding means. 4. A core box vent comprising a hollow cylindrical shell one end of which has been internally provided with means for limiting the axial movement of a filtering member, and a spiral resilient filtering member resting upon said supporting means, said spiral resilient filtering member be-' ing secured in place only by its spring tension.-

' PAUL BERNARD COPELAND.

HARRY L. MORRIS.

REFERENCES crran The following references are of record in'the file of this patent:

UNITED STATES PATENTS m ss 

